Teatcup liners are typically manufactured in a natural or synthetic rubber material. Rubber materials have many advantages connected to the elastic properties of rubber. These elastic properties are advantageous both during the manufacturing of the teatcup liner and during milking. The teatcup liner formed in a mould can easily be removed from the mould and the core shaping the inner space of the teatcup liner after the vulcanisation. However, the vulcanisation of the rubber requires a significant vulcanisation time before the rubber can be removed from the mould and the core. This is a limiting factor in the manufacturing of teatcup liners.
In order to speed up the manufacturing process, it is proposed to manufacture teatcup liners in a plastic material, i.e. Thermo Plastic Elastomers, TPE. The solidification time needed after moulding of such a plastic material is significantly shorter than the vulcanisation time needed for a rubber material. Consequently, by using such a thermoplastic material in the teatcup liner it would be possible to speed up the manufacturing thereof. A further advantage of a thermoplastic material is that it may be re-used. However, the elasticity of thermoplastic materials is generally smaller than the elasticity of rubber, which means that a teatcup liner with a conventional design would be difficult to mount in a teatcup shell.
It has been realised that a higher flexibility regarding the selection of material or materials in the teatcup liner may be achieved if the teatcup liner is manufactured as a number of separate components, which are then connected to each other when the teatcup liner is mounted.
The swedish patent application 0401484-1 discloses a teatcup of the kind initially defined. The teatcup includes a teatcup liner and a shell. The teatcup liner includes a first component forming a head portion and a second component forming a barrel portion, which second component also comprises a lower portion with an engagement member. The engagement member has the form of a flange. The first and second components are joined to each other by means of a snap joint or a thread joint so that either one of them can be changed when so required, while the lower portion is attached to the barrel portion by a melt joint. The teatcup liner of this prior art document is mounted in a shell, wherein the barrel portion is positioned in the shell. The lower portion of the barrel portion is gripped by a lower end of the shell. In order to make the engagement member of the shell to engage the engagement member of the lower portion of the barrel portion, the engagement member of the barrel portion is pulled below the engagement member of the shell.
There is, however, a need for an alternative solution to the engagement member described in the prior art.